Mower cutting unit having an internal motor

ABSTRACT

A greens mower having cutting units powered internally. The motor to power the cutting unit is located inside the cutting unit thus eliminating the need to balance the weight of the motor outside the cutting unit and also eliminating the need for belts, chains, gears or couplers to transfer power from the motor to the cutting unit.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates in general to an improved power driven mower, andspecifically to an electric motor to power a mower cutting unit whereinthe electric motor is housed inside the cutting unit.

2. Prior Art

Commercial mower applications have powered the cutting units through avariety of means. Early units were ground driven through a gear trainconnected to a pair of ground engaging wheels. Later, cutting units weredriven by an engine through chains, gears, drive shafts, or belts. Laterdesigns incorporated hydraulic motor drives or internal combustionengines which offered flexibility in applying power to multiple mowingunits attached to a prime mover chassis. In designs using hydraulicmotors, the motor was attached to the frame of the cutting unit andpowered the cutting unit through belts, gears or direct in-linecouplers.

Recently, electric motors are being used to power mower cutting units.These motors power the cutting units through belt, gear, or in-linecoupler connections. The cutting unit motor in these prior art mowers ispositioned either above and to one side of the cutting unit, or simplyout to the side of the cutting unit. In either case, the weight of themotor must be counterbalanced to ensure that the weight applied by thecutting unit is symmetric across the full width of the cutting unit. Ifthe weight of the motor is not counter-balanced, the actual height andquality of the cut of the grass can be adversely affected. This problemis especially evident for a cutting unit powered by an electric motor asthe motor can be heavy. In addition, the weight of the counter-balancemakes the overall weight of the cutting unit greater, which again canadversely affect the cutting quality and the life of the mower. Further,because the motor resides in an exposed position outside the cuttingunit housing, it can be easily damaged during the mowing process fromaccidental impact with objects near the surface to be mowed.

These conventional cutting unit motors utilize additional mounting framemeans, bearings, couplings and various hardware components to providepower to the cutting unit. Such external drive designs take up arelatively large amount of space, require frequent servicing, and arenot well suited to dirty or moist environments.

Accordingly, there is a need in the art for a mower that solves theabove-identified problems. Such a mower would not have the drawbacksassociated with counter-balancing the weight of the motor, externallymounting the motor, or the risk of damage to the motor due to limitedground and side clearance.

SUMMARY OF THE INVENTION

This invention relates to a mower having an improved cutting unit drivesystem using an electric motor, a hydraulic motor, or any other kind ofmotor. The novel cutting unit drive system is located within the cuttingunit instead of mounted outside the cutting unit. Although the inventionis described with respect to an electric motor, it will be understood bythose skilled in the art, that the advantages of this invention willapply to other types of motors as well.

Based on the above-mentioned problems in the prior art, it is an objectof the present invention to provide a motorized cutting unit in whichthe drive assembly is fully enclosed inside the cutting unit.

One object of the current invention is to distribute weightsymmetrically across the width of the cutting unit, thereforeeliminating the need for counterbalance weights and reducing weight ofthe overall cutting unit.

Another object of the current invention is to eliminate the belts,chains, gears or other couplers normally used to transfer power from amotor to the cutting unit.

A further object of the current invention is to provide cooling for themotor by using the air movement generated by the cutting unit blades,thus eliminating the need for a fan or other external cooling device andminimizing overheating concerns.

Still a further object of the current invention is to protect the motorunit from damage due to accidental impact when the mower is used to trimclose to objects such as trees, bushes, etc.

Still a further object of the current invention is to provide a motordrive assembly that is easily reached for servicing, repair andreplacement.

These and other advantages and features which characterize the presentinvention are pointed out with particularity in the following detaileddescription of the preferred embodiment, drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example and notlimitation in the figures of the accompanying drawings, in which likereferences indicate similar elements and in which:

FIG. 1 is a general drawing of mower;

FIG. 2A is an exploded view of a reel type cutting unit of the priorart;

FIG. 2B is a stylized drawing showing a first embodiment of the motorplacement in a prior art cutting unit;

FIG. 2C is a stylized drawing showing a second embodiment of the motorplacement in the prior art cutting unit;

FIG. 2D is a stylized drawing showing a third embodiment of the motorplacement in a prior art cutting unit;

FIG. 3 is a stylized drawing of the motor placement in a cutting unitaccording to the present invention;

FIG. 4A is a cross sectional view of one embodiment of the cutting unitaccording to the present invention; and

FIG. 4B is a cross sectional view of another embodiment of the cuttingunit according to the present invention;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a general illustration of a mower 10. The current inventionmay be used with the mower 10 as generally described below. Although theinvention is described with respect to the preferred embodiment, thoseskilled in the art will recognize that other versions of the cuttingunit embodying the current invention are possible and that the inventionis not limited to a specfic embodiment.

Although many constructions are possible, in the embodiment shown inFIG. 1, the riding greens mower 10 includes three wheels 20, 21, and 22.Two front drive wheels 20 and 21 are powered by a drive motor 30. Therear wheel 22 is positioned behind and between the two front drivewheels 20 and 21 and is pivotable to steer the mower 10. The cuttingunits 60, 61, and 62 are ideally reel cutting units. In FIG. 1, thecutting units 60, 61, and 62 are positioned ahead of each of the wheels20, 21, and 22 respectively. Of course other positions are possiblewhile still remaining within the spirit and scope of the invention. Thecutting units 60, 61, and 62 are optionally mounted on lift arms 1, 2,and 3. The operator selectively raises and lowers the lift arms 1, 2,and/or 3 depending on which cutting units 60, 61, and/or 62 the operatorwishes to use or to service. When in the lowered or operative position,the lifts 1, 2, and 3 allow free floating articulation of the cuttingunits 60, 61, and 62 to follow ground contours and to aid in providingfor an even cut over an undulating surface such as a golf course green.The drive motor 30 drives the mower 10, is powered by a battery (notshown), and is controlled by a controller 50.

In one embodiment, the cutting units 60, 61, and 62 are 11-bladereel-type cutting units. Cutting heights are adjustable from {fraction(5/64)}'ths to {fraction (9/16)}'ths inches. Nine, seven and five-bladecutting units are recommended for tees, approaches, fairways and sportsfields and also may utilize the advantages of the present invention.Although three cutting units 60, 61, and 62 are shown in FIG. 1, it willbe appreciated by those skilled in the art that each of the cuttingunits 60, 61, and 62 operate similarly, hence only one cutting unit (forexample cutting unit 60) will be discussed in detail.

FIG. 2A shows an exploded view of a typical mower cutting unit 60 of theprior art. The cutting unit 60 has a central shaft 66 that extends thewidth W₁ of the cutting unit 60. Disk shaped supports or spyders 64 areregularly spaced along the central shaft 66 and are secured to thecentral shaft 66 in a coaxial relationship. The spyders 64 support theblades 63 that extend the width W₂ of the cutting unit 60, but in ahelical or spiral manner. The cutting unit 60 includes supporting sideplates 40 and 42. A cross bar 44 extends between the two side plates 40and 42 and provides support for the overall cutting unit 60. Each sideplate 40 and 42 includes apertures 41 and 43 which receive a bearinghousing (not shown) that supports the ends of the central shaft 66. Theside plates 40 and 42 also provide mounting locations for the beltdriven motors (see FIG. 2B) and for the motors direct drive (see FIG.2C) of the prior art.

Turning now to FIGS. 2B through 2D, when a prior art cutting unit motor68 is attached to the housing 69 to power the cutting unit 60, it iseither disposed above the housing 69 as seen in FIG. 2B, or in line withthe cutting unit 60, as seen in FIGS. 2C and 2D. In either case, theweight of the cutting unit motor 68 should be counter-balanced to ensurethat the weight applied to the grass is symmetrically balanced betweenthe two points of support for the cutting unit 60. In some prior artcutting units 60, the weight of the side mounted motor 68 is balanced bya counter-balance 80 (FIGS. 2B-2D). In other prior art cutting units,however, the motor is counter-balanced by a second motor (not shown) inthe same position as counter-balance 80. The second motor is used todrive optional accessories to the cutting unit 60 or to provide back-uppower to the cutting unit 60. Both the counter-balance 80 and thesecondary motor add unwanted weight to the cutting unit 60.

In the disclosed embodiments, the width W₂ is typically 18 to 30 inches.If the weight of the cutting unit motor 68 is not counter-balancedacross the cutting unit width W₂, the actual cutting height and thequality of the cut will be adversely affected. This is especiallynoticeable for a cutting unit powered by an electric motor as thecutting unit motor 68 is heavy. In addition, the counter-balance 80makes the overall weight of the cutting unit 60 greater, which againadversely affects the cutting quality. A heavy cutting unit 60 cancompact the turf and leave unwanted marks. Further, the additionalweight of a counter-balance 80 to each cutting unit 60, 61, and 62 addsunwanted weight to the entire mower 10 reducing the time the mower 10can be operated before the mower battery 30 must be recharged.

In a typical prior art cutting unit as seen in FIGS. 2A-2D, the cuttingunit 60 consists of multiple blades 63 attached to a central shaft 66through a series of stamped steel spyders 64. This shaft 66 is generallymounted in bearings 70 at each end of the cutting unit 60 and is poweredby the cutting unit motor 68, either through power coupling mechanism 90or coupler 150. In FIG. 2B, the cutting unit motor 68 and thecounter-balance 80 are mounted above the central shaft 66 and the blades63 on housing members 69. A power coupling mechanism 90 transfers powerfrom the motor 68 to the blades 63 of the cutting unit 60. The powercoupling mechanism 90 can be a belt and pulley system, a gear train, achain or other type of power transfer mechanism.

FIGS. 2C and 2D show the motor 68 mounted in a direct driverelationship. In this embodiment, the power transfer mechanism 90 shownin FIG. 2B is replaced by a coupler 150 and the side mounted motorextends the overall width of the cutting unit 60 thus limiting sideclearance, and limiting the clearance G between the motor 68 and theground.

In fact, the side motor placement in both FIGS. 2C and 2D affects boththe ground clearance and side clearance of the entire mower 10. Sincethe side mounted motor 68 usually extends from the side of the cuttingunit 60 by length S of approximately 6 to 8 inches, if the motor 68 ismounted on the inside of one of the front cutting units 60 or 61 (FIG.1), the clearance between the two front cutting units 60 or 61,therefore, must be at least the length S of the side mounted motor 68,thereby limiting closer placement of the cutting units. Similarly, ifthe side mounted motor 68 is on the outside of one of the forwardcutting units 60 or 61 (FIG. 1), it extends an extra 6 to 8 inches fromthe side of the cutting unit and thus the entire mower 10, preventingthe mower 10 from making a close cut near bushes, fences, or otherobstructions.

The prior art arrangement shown in FIG. 2D includes all of the drawbacksof that shown in FIG. 2C and in addition the side mountedcounter-balance weight 90 increases the overall width of the mower 10even further. The side mounted counter-balance has a length C that itextends past the end of the cutting unit 60.

Referring again to FIG. 1, if both front cutting units 60 and 61 haveside mounted motors 68 and side mounted counter balances 80, the widthfrom one end of cutting unit 60 to the other end of cutting unit 61 isat least 2W+2S+2C, and no grass is being cut within the space 2S+2C. Ineffect, each cutting unit has an area on either side of it that cannotbe cut of S+C inches. Of course, a third cutting unit 62 mounted in thecenter rear of the mower 10 can cut the grass between the two frontcutting units 60 and 61, but the space to either external side of thecutting units 60 and 61 cannot be reached. If the mower operator iscutting grass close to the edge of a wall or a fence or otherobstruction, the mower 10 cannot cut any closer than S or C inches fromthe obstruction.

By contrast the current invention solves the problems of the prior artand is shown in stylized FIG. 3. The cutting units 60 of the presentinvention are of standard sizes so that they may be installed ontraditional mowers in place of prior art cutting units. In the presentinvention, the cutting unit motor 68 is located within the blades 63 ofthe cutting unit 60. The motor 68 is preferably a DC motor, but othermotors, both electrical and otherwise, can also be used. In thepresently described embodiment, the electric motor 68 and a gearreduction (not shown) are enclosed within a tube 72 having a diameter Mas small as two inches, thus fitting within the diameter of the spacecreated inside the blades.

As is apparent from FIG. 3, the novel internal motor arrangementeliminates the problems of the prior art caused by extended cuttingunits due to their motor mounting systems. The internal motorarrangement also solves the problems of the prior art caused by theadded weight necessary to balance the weight of the motor, but causingundesirable compaction of the grass. The cutting unit 60 shown in FIG. 3can be placed in close alignment with other cutting units of likeconstruction on a mower 10 using the same cutting unit positioning asthat shown in FIG. 1. Additionally, the power coupling mechanism 90 suchas a belt and pulley system, a gear train, a chain or other type ofpower transfer mechanism is not necessary in this novel internal drivesystem.

FIGS. 4A and 4B are cross-sectional views of two embodiments of thenovel cutting unit motor arrangement. FIG. 4A shows the internal motoras part of the rotating housing 72. In FIG. 4A, the rotating windings106 are attached to the inside of the rotating housing 72. The spyders64 are attached to the exterior of the rotating housing 72 and blades 63are supported by the spyders 64. The internal motor 68 is mounted on astationary shaft 71, and stationary motor windings 104 surround theshaft 71. For an electrically powered motor, power is delivered to theinternal motor 68 from a battery or generator (not shown) via power line108. Power from the power line 108 is routed to the rotating winding 106via slip rings 151, 152 and brushes 153, 154. The stationary shaft 71 isfixed to the housing 69 by fastening nut 102. The rotating housing 72 ismounted on bearings 70 so that it revolves easily around the stationaryshaft 71. The internal motor 68 is protected from elements such as dirtand water by seals 100 located between the stationary shaft 71 and therotating housing 72. The motor diameter D in this novel arrangement mayneed to be smaller than conventional cutting unit motors, but thewindings 104 and 106 in this arrangement can be made longer than in theprior art to compensate for the smaller diameter. The windings disclosedin the present invention may take advantage of the full width of thecutting unit W, typically 18 to 30 inches. Rotation of the cutting unit60 and thus the internal motor 68 serves to cool the internal motor andto minimize overheating, thus eliminating the need for fans or blowers.

FIG. 4B shows another embodiment of the internal motor 68 positionedinside the rotating housing 72 and cutting unit weldment 110. Thestationary shaft 71 extends axially through the housing and is journaledat each end by bearings 70. The cutting unit weldment 110 is fastened tothe rotating housing 72 with a series of fastening screws 112 or othersuitable fastening means such as pins or any device used for joining twoseparate parts. The stationary shaft 71 is held non-rotatably within thecutting unit 60. In this embodiment, the spyders 64, instead of beingwelded directly to the rotating housing 72 can be welded to the outercylinder 110, and everything inside the rotating housing 72 remains asdescribed in FIG. 4A. Consequently, the motor 68 and the gear reducerassembly (not shown) are held stationary. The rotating housing 72 ismounted on bearings 70 to easily rotate along with the cutting unitweldment 110 when power is applied. The embodiment disclosed in FIG. 4Bhas all of the advantages described with respect to the embodiment inFIG. 4A and includes the additional advantage that after removing thescrews 112 connecting the cutting unit weldment 110 to the rotatinghousing 72, the cutting unit weldment 110 including the spyders 64 andblades 63 are easily slid off of the internal motor assembly 68 forservicing or replacement.

In the foregoing specification, the invention has been described withreference to specific embodiments thereof. It will, however, be evidentthat various modifications and changes may be made thereto withoutdeparting from the broader spirit and scope of the invention as setforth in the appended claims. For example, an electrical overloadprotection means such as a fuse or other type of protection means can becontained internally inside the shaft of the cutting unit to prevent themotor from burning out. Other alternatives relate to using differenttypes of motors in the internal drive system. Still other alternativescan embody different types of blades. The specification and drawingsare, accordingly, to be regarded in an illustrative rather than arestrictive sense.

I claim:
 1. A gang mower comprising: a frame; a plurality of wheelsattached to the frame; a prime mover including an electric motor carriedon the frame, the prime mover to provide power to the gang mower; aplurality of cutting units attached to the frame, each cutting unithaving a weldment with a plurality of blades attached thereto via aplurality of spyders; a motor powering at least one cutting unit forrotation located within a hollow interior of a rotatable housing of atleast one cutting unit, the rotatable housing removably connected to theweldment of said at least one cutting unit by at least one screw, theweldment, spyders and blades of said at least one cutting unit beingremovable from said rotatable housing for servicing or replacement byremoval of said at least one screw.
 2. The gang mower of claim 1 furthercomprising a battery operatively connected to the prime mover, thebattery to provide power to the prime mover.
 3. The gang mower of claim1 further comprising a battery operatively connected to the motor, thebattery to provide power to the motor to drive the cutting unit.
 4. Thegang mower of claim 1 further comprising a drive axle operativelyattached to the prime mover and operatively attached to at least onewheel, and wherein the drive axle provides driving torque from the driveaxle to the at least one wheel.
 5. The gang mower of claim 1 wherein atleast one of the cutting units has a cutting position and a raisednon-operating position.